Here you can find information about the latest Moisture Design Years (MDY) project, which ended in 2022. The final report of the project can be found here (in Finnish, abstract in English). The previous building physics test years according to the FRAME project can be found here.
The page contains information on three types of assessments: time-dependent simulations, monthly calculations and steady-state conditions for condensation risk analysis.
Related materials can be downloaded from the links below.
Zip files are compressed folders that are extracted before use. In many cases, a suitable decryption program can be found pre-installed on the computer. One can also be installed, for example, here. Time-dependent Moisture Design Years are provided in several different file formats (csv, wac, xlsx).
Descriptions of the quantities can be found here (currently in Finnish only).
The moisture design year data contains information on the exterior conditions of buildings. Information on the indoor conditions of buildings is also needed for building physics calculations. More information about these can be found on this page. The computational moisture analysis method for structures related to time-dependent simulations is described here.
Time-dependent simulations
All Moisture Design Year files are available as a zip file from this link.
Time-dependent simulations refer to calculations that use hourly climatic data and they are commonly done using commercial programs such as WUFI, Delphin or COMSOL Multiphysics. The basic level of the heat and moisture transfer theory underlying these programs is presented in standard EN 15026. Additional guidelines on conducting the simulations are given in the final report of the project.
The selection method of the Moisture Design Years is currently given in the final report of the Construction Design Weather (RAMI) project. A shorter version is in a Finnish Building Physics Symposium paper (in Finnish).
The selection procedure of the Moisture Design Years proceeded by conducting multiple building physical simulations with a suitable simulation tool. Simulations were done for multiple wall structures facing both north and south, and also for a small number of roof constructions. The results were first analysed using subgroups of general wall type and orientation and then selecting years that had an average return time of 10 years in a wide range of situations. The calculations were done for four different Finnish locations of Vantaa, Jokioinen, Jyväskylä and Sodankylä (see map above); both current and future climatic conditions; and by using multiple monitoring points and performance indicators.
The new Moisture Design Years were selected for each location separately, in order to reach the targeted 10-year return period for each location. However, regarding mould growth in envelope structures, design years covering the whole of Finland have also been chosen. Commonly mould growth is the dimensioning criteria for envelope structures, but this is not the case e.g. with mould resistant materials, then the amount of moisture in the envelope structures is still limited. These calculations are done using the location-specific moisture design years.
The latest Finnish Moisture Design Years from the RAMI project are:
- Mould growth in envelope structures (whole Finland)
- Design calculations are always carried out using at least the design year Jokioinen 2011
- In the case of a concrete sandwich panel walls or a log wall with additional thermal insulation on the inside, the calculations are carried out using also the design year Jokioinen 2017
- In the case of a brick-clad timber frame wall (≥ 2 storeys), mould growth is examined also using the design year Vantaa 2017
- Limiting the amount of moisture (when mould growth is not a determining criterion)
- According to locality-specific design years
- Freeze-thaw cycles on facades and corrosion of reinforcing bars
- For the current climate according to locality-specific design years
- For the future climate according to the RAMI final report.
Regarding mould growth, design calculations are done using the future climatic conditions corresponding to the RCP8.5 scenario. In the basic case, the service life target of the load-bearing structures is at least 50 years, in which case the calculations use the above-mentioned design years for the RCP8.5-2080 climate.
Monthly calculations
The design year files are available as a compressed zip file from this link.
In this context, monthly calculations refer to quasi-steady state calculations in accordance with the SFS-EN ISO 13788 standard, also known as dew point calculations or the Glaser method. This calculation method includes only the conduction of heat and the diffusion of water vapour, i.e. it does not include many other key phenomena of heat and moisture transfer in building physics, such as rain, short- or long-wave radiation, the capillary transfer of moisture or the storage of moisture in building materials. However, the method is fast, calculations can also be made with spreadsheets or pen and paper, and it has been used in the construction industry for a long time.
The selection of outdoor air design years for monthly calculations is described in the final report of the Construction Design Weather (RAMI) project (in Finnish, abstract in English). In addition, a concise description of the topic has been prepared in the form of an Indoor Climate Seminar 2023 seminar article (Indoor Climate Seminar 2023, pp. 299–304, in Finnish). In short, the Glaser method was used to evaluate the performance of multiple wall structures with different outdoor climatic conditions. The year that consistently was closest to the 10-year return period for the amount of condensation was chosen as the design year. The years for monthly calculations were defined to start from beginning of July and end at the end of June.
Based on the reviews carried out in the Design Weather for Construction (RAMI) project, the locality-specific years for the winter season from July 2009 to June 2010 were selected as the design years to be used in the monthly calculations. The locality-specific design years correspond to the climatic zones in the Decree of the Ministry of the Environment 2010/2017 as follows:
- Climatic zone I: Vantaa
- Climatic zone II: Jokioinen
- Climatic zone III: Jyväskylä
- Climatic zone IV: Sodankylä
The condensation risk calculations for the winter season are made using the design years determined from the past 30-year period 1989–2018.
Design conditions for a stationary situation
In addition to hourly simulations and monthly calculations, the third design situation is the coldest short-term period of the year. The SFS-EN ISO 13788 standard provides a definition of the design conditions for the risk of condensation on the interior surface of structural components with a small thermal capacity, such as doors and windows, that are in contact with the room air. According to the standard, the design temperature of the outdoor air related to this design situation is the long-term average of the average temperature of the coldest day of the year.
Based on the calculations made in the Design Weather for Construction (RAMI) project, the following temperatures were determined as the long-term average of the coldest daily temperature of the year:
- Climatic zone I (Vantaa): -19 °C
- Climatic zone II (Jokioinen): -21 °C
- Climatic zone III (Jyväskylä): -25 °C
- Climatic zone IV (Sodankylä): -32 °C
The climatic zones mentioned refer to the climatic zones presented in the Decree of the Ministry of the Environment 1010/2017. Temperatures are 6 to 8 °C warmer compared to the outdoor air design temperatures for zone heating power specified in the Decree of the Ministry of the Environment 1010/2017.
During subzero temperatures, the water vapour concentration of the outdoor air is close to the saturation water vapor content in relation to ice. The relative humidity of the outdoor air in the above-mentioned design conditions can be assumed to be 97% RH in relation to ice.
The determination and results of the short-term frost period are presented in more detail in the final report of the Construction Design Weather (RAMI) project (in Finnish, abstract in English).